Fat hydrolysis



Feb. lo, 1948. M |TTNER 2,435,745

FAT HYDROLYS I S Filed May 15, 1941 3 Sheets-Sheet l INVENTOR Feb. 10, 1948. M. H. iTTNER FAT HYDROLYSIS Filed May 15, 1941 3 Sheets-Sheet 2 ATTORW 3 Sheets-Sheet 3 INVENTOR /I/or/'n [finer Zaan ATTORNEY Patented Feb. l0, 1948 FAT H YDROLYSIS Martin Hill Ittner, Jersey City. N. d.. assigner to Colgate-Palmolive-Peet Company, Jersey City, N. J., a corporation of Delaware Application May 15, 1911, Serial No. 393,650

8 Claims. (CL 26o-415) This invention relates to certain processes which are carried out under pressure and more particularly to the hydrolysis of fats with liquid water in autoclaves with the aid of elevated temperatures and pressures and to apparatus suitable therefor. y

In the hydrolysis of fats as now carried out at comparatively high temperatures and pressures, that is, generally upwardly of about 200 C., with hot water in liquid condition, it is advantageous to maintain the pressure reaction vessel full of liquid water and fatty matter undergoing hydrolysis. The reacting liquids are forced into the vessel by suitable means, commonly with the employment of high pressure pumps. With vessels completely lled `with liquid a very considerable amount of hydrostatic pressure is thus built up with great rapidity and would soon strain the vessel to the bursting pressure if proper provision were not made to guard thereagainst. It is thus necessary to provide pressure relief valves so that for each portion of liquid introduced under pressure a substantially equal volume of reacted liquid or liquids is allowed to escape through the,

relief valves. In this way an effort is made to maintain the desired pressure without undesired pressures being built up. Most pumps suitable for pressure work are prone to operate at at least somewhat irregular rates of delivery so that pulsating fluctuations of pressure are brought about and the eilect of such pulsating irregularities in the liquid feed of a pressure vessel are hammer-like in intensity where reciprocating pumps are used and placethe vessel at frequent intervals under undesirable and excessive stresses. The well-known practice of providing pumps with air-chambers filled with air in ordinary service, such as pumping water saturated with air, tends to even the flow the the pump discharge and to smooth out the pressure fluctuations. An ordinary air chamber on a pressure pump used in the hydrolysis of fats would be a very undesirable adjunct, as the air would gradually find its way 'into the pressure vessel and thus eventually completely' lose its cushioning function. Also, at the temperatures favorable for hydrolysis, air is very destructive to fats and will cause harmful darkening. and degradation of the fatty matter. It is even desirable, if not necessary practice, to subject the fat feed to special deaerating treatments to exclude every possible trace of air. If an inert gas were to be employed in an ordinary air chamber of a pump supplying degasified fat under pressure for hydrolysis the inert gas would 2 soon be dissolved and entralned in the feed and its advantage would soon be lost to the process.`

It has been proposed to employ a cushioning chamber of saturated steam within or directly connected to the upper part of the hydrolysis pressure vessel. l

It is an object of this invention to furnish an improved, novel and eective cushion against pulsating pressure fluctuations in introducing liquids into pressure vessels. A`

It is an object to provide a method of supplying liquids in non-pulsating ilow to high pressure vessels.

It is also an object of the invention to eilect certain economies in the process of hydrolysis both due directly to the cushioning method employed and indirectly to other advantages that are inherent in the process.

It is an object of the invention to provide improved and more economical methods of heating the materials to be subjected to hydrolysis and to provide improved and economical methods for introducing and contacting the reacting mal tion suitable for carrying out the invention.

the aid of heat and pressure is provided with a- Fig. 4 represents a sectional view of the upper part of an autoclave, partly cut away, with apparatus connected thereto providing a modified means of carrying out the invention.

Fig. 5 represents the upper and lower parts of an autoclave with apparatus connected thereto suitable for carrying out the invention.

Fig. 6 represents the lower part of an autoclave with modied means suitable for carrying out the invention.

The apparatus illustrated in Fig. 1 may be` more particularly described as follows: An autoclave or pressure vessel l suitable for carrying out countercurrent hydrolysis of fats with water with device 2 for distributing the wash water employed for extracting glycerine set free from the fatty acidsv produced in the process. A runoil pipe 3 connected with the bottom of the autoclave is provided with a suitable relief valve 4 for removal of the aqueous glycerine solution produced by the process. An inlet pipe is provided for introduction of the fat into the lower portion of the pressure vessel I. A runoff pipe 5 provided with a suitable relief valve 1 is connected with the upper part of the pressure vessel I for removal of fatty acids produced in the process. Tell-tale cocks 8 are provided so `as to facilitate the location of the interface 9 between the aqueous glycerine solution in the lower partof autoclave I and the fatty matter thereabove.

The fatty acid outlet is through a T I0 connecting with runoff pipe 5. T I0 is also connected with small pressure vessel II located above it. Pressure vessel II is provided with suitable tell-tale cocks I2 for determining the presence of liquid or vapor within pressure vessel II. Pressure vessel II may be provided with a pressure gage I3. Pressure vessel II is connected to a source of high pressure steam by means of pipe I4 and regulating valve I5. Thermocouples TC are provided as shown and for such locations as may have different or varylng temperatures which it may be desirable to determine.

The autoclave partially represented in Fig. 2 differs from that of Fig. 1 mainly in the fact that the small pressure vessel II of Fig. 2 is provided with one or more suitable heating elements I6, electric or of other kind, for applying controlled, additional heat to vessel I I and its contents. The upper part of pressure vessel II is supplied with suitable pipe connection I1 and valve I8 for adding steam to or removing it from vessel II. Thermocouples TC may be provided as and where needed, or desired.

An autoclave I is partially represented in Fig. 3 which has connected to it a side tube I9. The side tube I9 is represented as connected to the side of the pressure vessel near the top but may be advantageously attached thereto at other positions, as for example near the bottom or at some intermediate side position. Tube i9 may be advantageously extended downwardly and then upwardly so as to form a U-tube. Tube I9 may be provided near its lowest part with connection 20 and valve 2I attached thereto, and with valve 22 which may be used to control the passage of fluids through tube I9 to or from pressure tank 23. Pressure tank 23 is provided with suitable tell-tale cocks 24, or other means, for determining and controlling the interface between two different layers of fluids within tank 23 which is also provided with pressure gage 25 and connection 26 and valve 21.

Where tell-tale cocks are used in the apparatus of the invention, they may also serve other purposes, as for example the withdrawal of samples or for the withdrawal or addition oi other material as desired. Additional cocks, not shown, may be employed where and as desired.

Fig. 4 represents the upper part of pressure vessel lkconnected through T I0 with pipe 28 and pressure vessel II which latter is provided with tell-tale cocks I2 and in its upper part with hand controlled or automatic valve 29 and connection 30. Pipe 28 is provided with a drop so that as it extends outwardly from T I0, it also extends downwardly to the lpoint where it connects with vertical pipe 3l. Pipe 3i connects upwardly with pressure vessel 32 which is provided with a suitable water distributer 33 and outlet pipe 3,4 and control valve 35. The lower end of pipe 3| connects with injector 38 which is also connected through valve 38 to high pressure steam supply pipe 31. The discharge from injector 36 is through pipe 39 to distributor 2 in autoclave I.

Thermocouples TC may be provided and placed in any part of the apparatus of the invention where it may be desirable to obtain readings or records of varying temperatures at given points, or significant differences in temperature which may occur between different points within the apparatus.

The apparatus shown in Fig. 5 represents a high pressure vessel I, in section and partly cut away with novel means for heating and supplying the water and fat to be subjected to countercurrent hydrolysis. Vessel I is provided with water distributer 2 and fatty acid outlet pipe 5 and controlled relief valve 1 in its upper part, and aqueous glycerine runoff pipe 3 and controlled pressure relief valve 4 near its bottom. Fat inlet pipe 5 is also supplied near the bottom. Vessel I is provided with tell-tale cocks 8 to determine the location of the fat-aqueous glycerine interface 9, and with thermocouples TC at different locations to give the temperature of the contents at these locations.v A hot water pressure supply tank 40, provided with level indicator 4 I, is placed advantageously near the upper part of vessel I. Tank 40 may be supplied with water under pressure through pipe 42 which may be heated as desired by a supply of high pressure steam from pipe 43 regulated by means of valve 44 and perforated coil 45 located in the lower part of vessel 40 beneath the surface of a water layer maintained in tank 40. The water heated in tank 40 may be supplied, as desired, to distributor 2 by means of pipe 46 and control valve 41. The upper part of tank 40 will, in normal operation, be filled with steam under pressure. Thermocouples TC are provided to indicate the temperature of the water layer in tank 40 and of the steam above it. It is preferable to maintain the temperature and pressure of the steam in tank 40 sulciently higher than the temperature and pressure of thev fatty acids in the upper part of vessel I to impel water to iiow through pipe 46. Tank 4I)a also has a pressure gage 25 and a suitable steam relief valve 28 connecting with pipe 30. The equipment attached to the lower part of vessel I provides a novel method of heating and supplying the fat for hydrolysis. The fat under pressure is supplied through pipe 48 and is heated in heater 49 and passes by pipe 58 into pressure tank 5| located preferably near the bottom of autoclave I and connected therewith by hot fat supply pipes 53 and 55 and supply control valve 54. Presand control valve 53 to the supply of nitrogen or other substantially inert gas maintained in the upper'part of tank 5I at a suiiiciently higher pressure than is maintained in vessel i to impel fat to flow through pipe 53. Tank 5| is also provided with thermocouples for indicating the tem perature of its contents.

The apparatus shown in Fig. s illustrates the.

lower part of an autoclave for countercurrent hydrolysis of fats. The fat supply, which may be somewhat preheated is brought to pump llwhich forces it through pipe II to injector Il which is connected through valve ll to high pressure steam supply pipe 81. The fat is impelled by steam injector 3l` through pipe l2 where itbecomes heated to the desired temperature and through distributer 63 into pressure tank u which serves as a come and go reservoir for hot fat. Part of the steam used for injecting and heating the fat becomes condensed to liquid water upon transferring its latent heat to the fat. The water thus condensed settles in the bottom of tank 64 beneath the fat-water inter` face 65, and excess steam rises through the fat and collects above the steam-fat interface il and may be drawn off as desired through controlled reliefvalve 29 and pipe il.; Water containing some glycerine is conducted from the bottom of tank 64 through pipe 10 and control valve 1I to a water distributer 12 located preferably intermediate between interface 9 and water distributer 2 near the top o f .vessel I,`at a place where the Vconcentration of the countercurrently falling glycerine washings are not greatly different from the concentration ofy glycerine in the water enteringl through distributer12. P19611 connects with the fatty pha'sewithin tank 64` so that a supply of hot fat may be permitted toV l enter vessel v,I Icontinuously,or as desired, with non-pulsating flow, bythe operation of valve and be distributed thrcugndistribtr es preferr ably substantially beneath the fat-water interface 9 'and well above outlet pipe 3.

The operation of the process as performed'in the apparatus of Fig. 1 may be as follows: VFat 'to be hydrolyzed, suitably heated, preferably aqueous glycerlne solution, thus increasing the percentage of glycerine in this solution at the same time setting up some countercurrent hydrolysis as the fat globules rise through the water layer. enter sufficiently above the outlet pipe 3 so that the incoming fat will not become emulsied near the bottom of vessel I with the glycerine solution which ordinarily is being discharged simultaneously through pipe 3 and valve '4. Water, suitably heated, is forced into the upper part of vessel I through a suitable distributer 2 so as to be finely dispersed and to offer large surface contact between Athe water droplets thus formed and the fatty matter from which the glycerine is to be extracted by the countercurrent action of descending water and rising fatty matter. 'Ihe interface 8 between aqueous glycerine solution and fatty matter is preferably maintained at a ysubstantially constant level by the proportion of It is also desirable to cause the fat to adam therein. either of which would interfere seriously with good countercurrent washing by the formation of emulsions in the zone for countercurrent washing, or by actually depleting the effective wash water and the dissolved water, both.

of which are essential to emcientcountercurrent hydrolysis. The fatty acids passing through l' Il are in contact at or near this point with steam in substantial pressure equilibriumwith the contents of vessel I. Steam from a source having a pressure always somewhat higher than the pres- -I and controlled pressure relief valve 1. Other means than valve 1, and separate therefrom, may be provided for escape of the excess superheated steam.

The high pressure steam entering through pipe Il and valve I5 is released to a somewhat lower pressure on passingthrough valve IS and is therefore superheated.` Operation of the process will be greatly facilitated byiobserving from time to time simultaneous temperature readings of the high pressure steam in pipe I4, the superheated steam in vessel I I, and the fatty acids saturated with dissolved'water in the upper part of vessel I. Withthese data constantly available, it will be easy to so control valve I5 that the superheated steam in vessel II shall always have a slightly higher temperature than the outgoing fatty acids. The degree of this excess temperature is limited on the low side, only by the delicacy of available control instruments, 'a small fraction of a degree of excess temperature being all that is required, inasmuch as it is all the excess necessary to maintain a volume of superheated steam and to retain the liquids within vessel I in a liquid condition and to prevent any formation of vapor within the'liquid layers' in vessel I which would interfere with countercurrent hydrolysis. Itlmay thus be seen, that with regulation that may readily be provided, it will be comparatively easy to avoid the' necessity of supplying any large amount of steam through valve I5, and that the amount of excess steam allowed to escape through valve 'I with the fattyacids may be kept down close to none at all.

The apparatus of Figa-2 may be operated as described for that of Fig.v 1 *but may also be operated without the aid of an outside source of high pressure steam by employing the heating elements I6 around vessel II. vIn countercurrent hydrolysisl itl is essential for smooth operation that the 'temperatures'of lthe liquids within the pressure vessel shall be at least slightly below the temperature of saturated steam at the corresponding pressures, or conversely, that these liquids at whatever temperatures they may have shail be subjectedto at least some excess pressure over the pressure corresponding to the pressure of saturated steam at Vtheir temperatures. 1n this way any excess pressure employed, however small. will prevent the harmful formation of vapor within the liquid layers. the avoidance of which is essential to the smooth operation of countercurrent hydrolysis. It can now be seen that, unless an unnecessarily large excess pressure is employed in vessel I, the application of einem a moderate amount or excess heat to vessel Il. applied with the aid of heating elements I3, will result in the formation of steam by the vaporization of a small portion of the dissolved water in that portion of the fatty acids resulting from the process which may enter vessel II. and that this steam will be snperheated. The formation of this steam will drive the fatty acid-steam interface downward toward T I3. If, now, heat be applied continuously to vessel II in amounts so controlled that the temperature of the steam in the upper part of vessel II will he at all times slightly higher than the temperature of saturated steam at the pressure employed in the upper part of vessel I, a superheated steam phase with a desirable cushioning effect against pulsating pressure fluctuations will be maintained in vessel Il while the liquid layers within vessel I will remain in the liquid state.

The modified apparatus shown in Fig. 3 illustrates part of the features of the invention. The upper part of autoclave I is shown partly in section. partly cut away. It is provided with water distributer 2 and fatty acids outlet pipe 3 and regulating preure relief valve 1. Pipe I8 connects vessel I with vessel 23, valve 22 being open during operation. The lower part of tank 23 is filled with water and so also is the connecting portion of pipe I3 and in fact the greater part of pipe I9. A certain amount of fatty matter will fill that portion of pipe I9 nearest to vessel I, taking a position in one leg of U-tube I9 above the water therein contained. In beginning operations with this equipment valve 22 may be closed and tank 23 filled with water. Nitrogen or other substantially inert gas under pressure may then be run into tank 23 through valve 21 and pipe 23 on opening valve 22 while at the same time about two-thirds to three-quarters ofthe water content is permitted to flow out of pipe I3 through valve 22. The inert gas may be added to a pressure about equal to that in vessel I, after valve 22 has been opened, and tank 23 with its content of inert gas will serve as an efficient cushion to tank I .protecting it against stresses due to pulsating pressures. During the operation of this equipment, the interface in pipe I3 between water and fatty matter will move down and up with the pulsating increasing or decreasing pressures.

The apparatus illustrated in Fig. 4 embraces certain important novel features which also permit of a novel method of carrying out hydrolysis. The fatty acids resulting from the hydrolysis passing out of the top of autoclave I and through T I and pipe 28 reach vertical Ipipe 3I and work upwardly therein to pressure tank 32 which is maintained full of liquid, and thence outwardly through pipe 34 and controlled `pressure relief valve 35. In passing upwardly in tank 32'r the hot fatty acids come into direct heat exchange relationship with a ow of water supplied through water distributer 33, thus heating the water with heat absorbed from the hot fatty acids. The outgoing fatty acids lose, in this way, the greater part of their dissolved water which is thus added to the water supplied through distrlbuter 33, and any remaining undissolved water separates from the outgoing fatty acids between distributer 33 and outlet .pipe 34. The undissolved water in tank 32 works downwardly through pipe 3| to steamwater injector 33 where it comes into intimate, direct contact with high pressure steam supplied through pipe 31 and valve 33. The action of injector 36 produces a strong flow of liquors through pipe 33 to and through distributer 2 bringing the 1| temperature ofthe water and fatty matter dise charged through distributer 2 up close to the temperature of saturated steam at the pressure maintained in the upper part of vessel I. This `current results also in circulating a certain persed into a very fine state of subdivision, and c on entering vessel I is so thoroughly distributed that it contributes at once, and thereafter. the highest degree of eiiiciency to the washing action of the wash water falling countercurrently downward through the rising fat. An incipient degree of emulsiilcation. or an approach thereto, is not harmful in this .part of the apparatus or to this stage of the process where the hydrolysis is already substantially complete. At the temperature and pressure of the operation, fatty matter and undissolved water, even though partly emulsified separate rapidly from one another when removed from an emulsifying influence. and the fatty acids entering tank 32 from pipe 3l are substantially free from emulsiilcation and are almost free from any but dissolved water and the countercurrently flowing water which is passing downwardly through pipe 3l. If, for example, a pressure of about 500 pounds per square inch is maintained in vessel I and a temperature very slightly lower than the temperature of saturated water vapor at that pressure, and steam is supplied through pipe 31 to valve 33 at 600 pounds per square inch. or somewhat higher, the contact betweer` steam. and water and fatty acids in injector 36 and pipe 39 will heat the water and circulating fatty acids substantially to the temperature of the hot expanded steam. During this operation a certain amount of the hot steam in giving up its latent heat to heat the water and circulating fatty acids will be condensed, thus adding to the total amount of hot water sent to distributer 2. The amount of water thus condensed from the steam is a direct function of the pressure, temperature and amount of steam employed. and of the fresh water added through distrlbuter 33 so that it becomes a matter of adjustment of these controllable factors to determine the total ,amount of water passingv through distributer 2,

and to control it at will. Injector y36 may be a single stage or a multi-stage injector. It is desirable to supply an additional pressure tank II above T I0. With the method of operation here shown. it is advantageous to inject a slight excess of steam through injector 33 which will pass as such through dstributer 2 and rise through T I0 into tank II. The amount of steam passing thus into tank II need not be at all large and this excess steam, which will be very slightly superheated over the temperature maintained in the top of vessel I. may be suitably released through valve 29 and connection 33 and be utilized elsewhere in the process or for other purposes. The drop in pipe 23 from 'l' I0 to pipe 3l is so that steam will flow only towards tank II, and liquid water towards pipe 3|. Thermocouples in the high pressure steam line 31, in the fatty acids in pipes 34 and 3l. and in the upper part of vessels I and' Il. and elsewhere, permit of easy adjustment, and are conducive to the smooth running of the process and permit the operation of countercurrent hydrolysis within a narrow range of temperature without any danger of un- A,

usava toward variations vin either temperature or pressure;

The apparatus of Figs. and 6 provide novel means and methods for supplying hot water and hot fat to vessel I substantially without pulsations orpressure variations. Auxiliary water and fat reservoirs 40, 5| and 84 with their contents of hot water orl hot fat are maintained at pressures sufficiently above the pressure within vessel i to impel the water and fat to flow into the autoclave. The hot water and hot fat. areA released as desired in substantially non-fluctuating flows through inlet control valves 41, Il, 68 land 1i. 'These reservoir tanks are themselves provided with cushioning means which though having practically no direct influence on changes in pressure in vessel I. do nevertheless have a salutary influence on the pressure within the auxiliary reservoir tanks.

This application is a continuation-impart of my prior pending applications Serial No. 240,037 filed November 12, 1938, and Serial No. '311,584 filed December 29, 1939. y l

The apparatus may be and should be provided with eiiiclent heat insulating material at all parts where heat radiation losses may otherwise be substantial or harmful.

Although the invention has been described and illustrated with reference to specific means and operations, the invention is not limited to the specific means and operations referred to which are only illustrative of the'invention described hereinabove and defined in the following claims.

I claim:

1. In the process of hydrolyzing fats by causing liquid fatty matter and liquid water to flow countercurrently in direct contact in an autoclave under suitable high temperature and pressure to form an aqueous glycerine solution in the lower part of the autoclave and fatty matter thereabove. the method of heating water for said countercurrent hydrolysis and dispersing it in said fatty matter which comprises intimately contacting water with steam to heat said water, and utilizing pressure of said steam to impel a flow of said heated water at least largely in liquid form into said fatty matter at a plurality of points near the top of the autoclave, said hot water being at a temperature and pressure sumciently higher than the temperature and pressure of the fatty matter to effect dispersion of said water in said fatty matter with the aid of uncondensed steam.

2. In the process of hydrolyzing fats with water, to fatty acids vand glycerine with the aid of heat and pressure and countercurrent washing of glycerine from the resulting fatty matter with the aid of hot water, the method of dispersing said water to facilitate said washing which comprises mixing the water with a portion of said fatty acids and forcing the mixture of fatty acids andwater under pressure with the aid of direct steam into said fatty matter at a plurality of points, the proportionof fatty acids to water being suillcient to aid the dispersion of Y said water in said fattymatter.

3. In the process of hydrolyzing fats by causing fatty matter and water to flow countercurrently in direct contact in an autoclave under high temperature and' pressure, the method of supplying heated fats for said countercurrent flow which comprises maintaining a quantity of hot fatty matter in direct contact with substantially inert gas, maintaining the pressure of said inert `gas substantially higher than the pressure in said autoclave, utilizing the pressure of said inert gas temperature and pressure higher than the temperature and pressure in said autoclave, segregating excess steam from said heated fatty matter, and utilizing the pressure of said excess steam to force a flow of said heated fatty matter intosaid autoclave.

5. In the process of hydrolyzing fats by causing fatty matter and water to now countercurrently in direct contact in an autoclave under high temperature and pressure, the method which `comprises heating fatty matter before it is forced into said autoclave at least substantially up to temperature for said countercurrent hydrolysis by direct contact with an excess of steam at a temperature and pressure higher than the temperature and pressure in said autoclave, segregating excess steam from said heated fatty matter. permitting undissolved hot water condensed 4from said steam together with any glycerine derived from said fatty matter dissolved therein to settle from fatty matter thus heated, and utilizing the pressure of the segregated steam to force fatty matter thus heated and segregated into the autoclave where it is subjected to said countercurrent hydrolysis.

6. In the process of hydrolyzing fats by causing fatty matter and water to flow countercurrently in direct contact :ln an autoclave under high temperature and pressure, the method which comprises heating fatty matter before it'is forced into said autoclave at least substantially up to temperature for said countercurrent hydrolysis by direct contact with an excess of steam at a tem- Y perature and pressure higher than the temperature and pressure in said autoclave, segregating excess steam from said heated fatty matter, permitting undissolved hot water condensed from said st eam together with any glycerine derived from said fatty matter dissolved therein to settle from the heated fatty matter, forcing hot water into said autoclave near the top thereof, forcing said heated fatty matter into said autoclave near the bottom thereof and forcing said settled water and glycerine into said autoclave between the places of introducing said water and fatty matter.

7. In the countercurrent process of hydrolyzing fats' with waterto fatty acids and glycerine at elevated temperature and pressure, the method which comprises contacting hot fatty acids produced [in the countercurrent process with water at lower temperature to eect cooling of the fatty acids and heating of the water by direct heat exchange, supplying additional heat to said water by. direct steam, and contacting said heated water by countercurrent flow with fatty material to be hydrolyzed.

8. The method of hydrolyzing fats which comprises intimately contacting fatty material with water by countercurrent flow in an autoclave at elevated temperature and pressure to form fatty acids and glycerine, withdrawing fatty acids from the upper part of said autoclave, withdrawing glycerine from the lower part of said autoclave, subjecting the fatty acids formed while still under 11 l pressure to .partial cooling by direct contact and mixing with water having a lower temperature whereby the water is heated and the fatty acids are cooled, supplying additional heat to said water by inJecting steam at a higher ,temperature and pressure into contact therewith, and dispers'ing said heated water and injected steam into fatty material in said autoclave for countercurrentilow with fatty material to be hydrolyzed.

MARTIN HILL ITTNER.

REFERENCES -CITED The following references are of record in the ille oi' this patent:

UNITED STATES PATENTS Number Name Date 2,233,845 Mills Mar. 4, 1941 1,684,489 Halloran Sept. 18, 1928 2,009,347 Sheldon July 23, 1935 2,281,534 Davey Apr. 28, 1942 2,267,750 Robisch Dec. 30. 1941 OTHER. REFERENCES Elements of Chemical Engineering." Badger l: McCable, page 84, published in New York in 1931 by McGraw Hill Book Co.

Perry, Chemical Engineers Handboo ed. 1,

15 1934, pages 1874 and 1875. 

